The invention relates to a microwave oscillator stabilized by a dielectric resonator constituted on the one hand by a housing accommodating the dielectric resonator circuit and comprising a fixing surface and on the other hand by a support having an outer surface, on which the housing is secured.
The development of new materials having high dielectric constants (barium or zirconium titanate) and exhibiting very low microwave frequency losses and temperature coefficients equal to zero or slightly positive has led to the formation of a new generation of microwave oscillators, i.e. oscillators stabilized by a dielectric resonator. These oscillators operate at a fixed or slightly adjustable frequency and are characterized by a high stability with respect to the frequency and to the output level as a function of temperature, a high electric efficiency due to the use of field effect transistors, a high spectral purity and the possibility of using microband technology, thereby enabling the achievement of a small weight and a small volume.
This oscillator type is used for many applications in instrumentation, telecommunication, radar etc. In certain applications, a given spectral purity of the microwave frequency signal has to be maintained during aleatory vibrations. The mounting technology has therefore to be adapted to these limitations and more particularly the dielectric resonator has to be firmly secured on its circuit and the metallic and dielectric environment of this resonator has to be very rigid and stable because any variation of the metallic surfaces surrounding the dielectric resonator produces variations of the oscillation frequency. Especially, the distance h between the dielectric resonator and the cover of the housing is very critical in this respect. The Applicant has shown, for example, that for a distance h of 3 mm a simple differential variation .DELTA.h of a few tens of 10.sup.-3 .mu.m produced a reduction of the phase noise of about 15 dB at 1 kHz of the frequency of the oscillator centred at 14 GHz. Therefore it is of major importance to design an extremely rigid housing, which cannot be realized merely by means of an increase of the metallic thicknesses without unfavourably increasing the weight and the volume of the housing.